The focus of the operation was Bulgaria, where 150 police officers participated in operations to arrest 47 suspects. Nine more were arrested in Italy, as well as two in the USA, two in Spain and one in Poland.

The Bulgarian ring leaders are linked to criminal cells in Kenya, South Africa and the USA. The group's methods included recruiting and training petty criminals to make illegal cash withdrawals.

Europol says the gang used cards skimmed in EU countries to loot accounts in non-EMV-compliant regions such as the US and Africa.

Rob Wainwright, director of Europol, says: "This investigation has given us a unique insight into the 'skimming phenomenon'. It highlights the fact that illegal credit card transactions outside the EU are a major part of the problem, and that as long as cards have magnetic strips they will be vulnerable to skimming."

EU Commissioner for Home Affairs, Cecilia Malmström, echoed his sentiments: "This major new criminal phenomenon exposed in this case, with criminals transferring data stolen within the EU to accomplices in countries and regions elsewhere in the world, is of great concern. The financial losses involved harm millions of citizens and the economic interests of many of our banks and businesses. The European Commission...is committed to exploring all possible opportunities to reverse the effects of this new problem."

The US Federal Reserve Bank of Atlanta has been leading the push for the US to shift its reliance from mag-stripe technology. Writing in the Fed's Portals and Rails blog in October last year, EVP Richard Oliver said: ""If we want to mitigate the possibility of the United States being a centre of card fraud and enable our consumers and business folks to travel abroad more easily, it may be time to charge someone in government with developing a well-thought-out, participatory, multi-year plan to move this country to the emerging global payments card standard,"